1. Field of the Invention
This invention relates to a fuel control device of an engine which controls quantity of fuel that is supplied to an engine of an automobile or the like.
2. Discussion of the Background
In the conventional device of this kind, pressure in an intake pipe of an engine is detected by an intake pipe pressure detecting means which is converted to a pressure data. Determination is made whether the engine is in transient state, by comparing the pressure data and a threshold value for determining a transient state. Corresponding with a result of the determination, the fuel injection quantity is calculated based on the pressure data. The fuel of this fuel injection quantity is simultaneously supplied by injection to the engine synchronizing with a predetermined crank angle. The acceleration state of the engine is swiftly detected by detecting the change quantity of an output of a throttle opening degree sensor. The fuel is simultaneously supplied to the engine not synchronizing with the crank angle.
Since the conventional fuel control device of an engine is constructed as above, a ripple variation of the pressure data is significant when the engine load is in heavy load range. Therefore the threshold value for determining a transient state is set at high value considering the ripple variation so that the transient state is not erroneously detected by the ripple variation. Henceforward, the detection sensitivity is lowered. Especially in the acceleration time of the engine in its light load range, although it is possible to control the nonsynchronizing injection by a throttle opening degree sensor at an initial state of the acceleration, the transient state detection for increasing the synchronized injection quantity is retarded. Therefore it is not possible to supply the fuel quantity in correspondence with the transient state to the engine with high response. The air-furl ratio control in the transient time is delayed, and the air-fuel ratio becomes unstable, which worsens the running performance of the engine. Furthermore, since the conventional system utilizes the throttle opening degree sensor, the cost for the control device is increased.